EP0584708A1 - Polyfunctional demulsifiers for crude oils - Google Patents

Abstract

The invention relates to the use of alkoxylated fatty amines and fatty amines of the general formula (I), <IMAGE> where A is a radical of the formula (II)-(V) <IMAGE> with R = C6-C22-alkyl, x is a number from 5 to 40, y is a number from 5 to 70 and that z is equal to 0-70% by weight of ethylene oxide, relative to compounds of the formula (I) with x ethylene oxide units and y propylene oxide units, as demulsifiers, corrosion inhibitors and/or pour point depressants in crude oils. There are radicals of the general formula (I) without A all the free valencies of the nitrogen atoms of the formulae (II) to (V). The compounds of the formula (I) are prepared by reacting amines of the formulae (II) to (V) with ethylene oxide and propylene oxide, with addition of bases such as alkali metal hydroxides.

Description

The extracted crude oil usually contains a number of disruptive accompanying substances, such as water, inorganic salts and paraffins and asphaltenes, which are usually removed before transport or storage. Water-in-oil emulsions often cause corrosion and microbiological growth in the water-wetted parts of the pipes and tank systems. By using suitable demulsifiers, the water-in-oil emulsions are split and thus the water and salt content of the crude oil is reduced. If the crude oils contain large amounts of paraffins and asphaltenes, they have a high pour point, which in some cases leads to deposits in the production probes and especially in the pipelines and can bring the production and pumping of the crude oil to a standstill.
In order to avoid these disadvantages, it has previously been customary to add special additives to the crude oil for demulsification, corrosion inhibition, disinfection and inhibition of paraffin and asphaltene deposition.

US-A-2 557 081 describes the use of oxyalkylated alkylphenol formaldehyde resins as demulsifiers.
From US-A-2 674 619 and US-A-2 677 700 the use of polyalkylene oxide block polymers as demulsifiers is known.
US-A-3 974 220 describes the use of alkyldiamine salts and alkylammonium compounds as demulsifiers with a corrosion-inhibiting effect.
EP-A-186 009 discloses the use of oxyethylated amines, also in combination with ethylene copolymers, as pour point depressants.

Despite the known additives, it is still desirable to have compounds which enable use as a corrosion inhibitor, demulsifier and pour point depressant.

wobei
A ein Rest der Formel (II) - (V)

mit R gleich C₆-C₂₂-Alkyl, vorzugsweise C₈-C₁₈-Alkyl
x eine Zahl von 5 bis 40, vorzugsweise 8 bis 20,
y eine Zahl von 5 bis 70, vorzugsweise 10 - 30, und z gleich 0 - 70 Gew.-%, vorzugsweise 0 - 40 Gew.-% Ethylenoxid bezogen auf Verbindungen der Formel (I) mit x Ethylenoxideinheiten und y Propylenoxideinheiten,
als Demulgatoren, Korrosionsinhibitoren und/oder Stockpunktserniedriger.The invention relates to the use of oxyalkylated fatty amines and fatty amine derivatives of the general formula (I)

in which
A is a radical of the formula (II) - (V)

with R equal to C₆-C₂₂-alkyl, preferably C₈-C₁₈-alkyl
x is a number from 5 to 40, preferably 8 to 20,
y is a number from 5 to 70, preferably 10 to 30, and z is 0 to 70% by weight, preferably 0 to 40% by weight, based on compounds of the formula (I) with x ethylene oxide units and y propylene oxide units,
as demulsifiers, corrosion inhibitors and / or pour point depressants.

The free valences of the nitrogen atoms of the radicals of the formulas (II) to (V) contain radicals of the general formula (I) without A.
The compounds of the formula (I) are prepared by reacting amines of the formulas (II) to (V) with ethylene oxide and propylene oxide with the addition of bases, such as alkali metal hydroxides.

The reaction takes place in several stages at temperatures in the range from 100 to 150 ° C., preferably 130 to 140 ° C. The amount of catalyst / base used is usually 0.5 to 3.0% by weight, based on the starting amine used. The molar amount of ethylene oxide and propylene oxide per mole of starting amine corresponds to the values given for x and y and the weight percentages given for z.

In the preferred production form of the oxyalkylated fatty amines and fatty amine derivatives of the formula (I), the amine of the formula (II), (III), (IV) and / or (V) which is initially introduced is heated to a temperature of approximately 130 to 140 ° C. and initially reacted with 1 mole of ethylene oxide per equivalent of NH function, whereupon the alkali metal hydroxide is added as a powder or in the form of an aqueous solution. When adding an aqueous, preferably 40% by weight aqueous solution, it is necessary to remove the water present before adding the remaining amounts of ethylene oxide. This is done in a simple and gentle way by applying a vacuum. The alkalized oxethylate obtained is then also reacted at 130 ° C. with the desired residual amount of ethylene oxide. After the addition of ethylene oxide has ended, the reaction mixture is kept at a temperature of approximately 130 to 140 ° C. for the after-reaction for several hours. The end of the reaction is indicated by constant pressure at approximately one bar. It has been shown that because of the exothermic reaction, it is advantageous to add said residual amount of ethylene oxide in several stages. This can be achieved by gradual addition in small amounts or continuous addition. The reaction temperature is in the range of 130 to 140 ° C and the pressure is approximately 3-4 bar. Depending on the amount of ethylene oxide, the addition takes several hours, on average 6-8 hours. When the addition is complete, as mentioned, the reaction mixture is kept at a temperature of 130 to 140 ° C. for several hours, preferably 2 hours. The end of the reaction is indicated by constant pressure at approximately one bar.
The finished oxethylate obtained is reacted with propylene oxide in a further stage. This propylene oxide is added at a temperature in Range of 100 to 150 ° C, preferably in the range of 130 - 140 ° C, with the desired amount of propylene oxide is usually added to the extent that its reaction takes place. During the addition, the pressure in the reaction vessel rises to approximately 3-4 bar. After the addition, which generally takes up to 10 hours, the reaction mixture is kept at a temperature in the range from approximately 130 to 140 ° C. until the end of the reaction is indicated by constant pressure in the range of one bar.

The ethoxylated and propoxylated compounds of the formula (I) thus prepared can be reacted with additional ethylene oxide in a further step. The amount added is in the range from 0 to 70% by weight of ethylene oxide, based on compounds of the formula (I) with x ethylene oxide units and y propylene oxide units. This additional addition of ethylene oxide after the propoxylation has already taken place is carried out analogously to the reaction with propylene oxide, it being possible to dispense with an additional alkalization.
The compounds of the formula (I) are used as additives for crude oils, and they act both as demulsifiers, corrosion inhibitors and lower pour points.

Manufacturing examples

The terms used below for characterization, such as alkali number and iodine color number, are determined or determined as follows:

Determination of the alkali number:

To determine the alkali number, given in mg KOH / g substance, weigh 0.1 to 0.5 g of the sample in a 150 ml beaker, dissolve in 60 to 80 ml ethanol and titrate with 0.1 N ethanolic potassium hydroxide solution. The end point is displayed potentiometrically (devices: Metrohm Titroprocessor 682, Dosimat 665 with combined pH glass electrode).

Iodine color number:

The iodine color number means the concentration of free iodine in an iodine-iodide-potassium solution (in mg iodine per 100 ml of iodine-iodine-potassium solution) and serves to identify the color or translucency of this solution and similar liquids. The basis for the determination of the iodine color number is the iodine color scale (comparison tube). Literature: DIN 53403.

The following exemplary embodiments illustrate the present invention without restricting it.

example 1 1st stage:

In a 1 liter stirred autoclave 50 g (0.19 mol) of tallow fatty amine (amine of formula (I) with R = C₁₄- (5%), C₁₆- (30%), C₁₈- (5%) - alkyl; iodine number = 45; alkali number: 210 mg KOH / g substance; molecular weight: 267, initially charged and heated to 130 ° C. At this temperature, 16.7 g (0.38 mol) ethylene oxide (EO) are added. The pressure rises to 4 After the addition has ended, the mixture is left to react for 2 h at 130 ° C. The end of the reaction is indicated by constant pressure at 1 bar.

2nd stage

The contents of the autoclave are then mixed with 3.2 g of a 40% aqueous KOH solution and the water is removed at 80 ° C. in the course of 2 hours in a water jet vacuum. Ethylene oxide (EO) (166.3 g, 3.78 mol) is metered into the alkalized fatty amine oxyethylate to the extent that it reacts. The pressure in the autoclave rises to 3-4 bar, the reaction temperature is between 130 and 140 ° C (reaction time 8 h). After the addition has ended, the mixture is reacted for a further 2 hours at 130 ° C., whereupon the pressure remains constant at 1 bar and indicates the end of the reaction.

3rd stage

Without further isolation, propylene oxide (PO) (364 g, 6.27 mol) is now metered into the above product to the extent that it reacts. The pressure rises to a maximum of 3 bar, the temperature to a maximum of 130 ° C. The addition is complete after about 10 h; the after-reaction takes place at 130 ° C. for 2 h, whereupon the pressure remains constant at 1 bar and indicates the end of the reaction.
The product thus obtained is a light yellow, pasty mass with an alkali number of 22.5 mg KOH / g substance and a cloud point of 44.1 ° C (according to DIN 53917).
All cloud points were determined with a 5 g weight (product) on 25 g of a 25% aqueous butyl diglycol solution.

Example 2:

The product is produced analogously to Example 1.

Amounts used: 1st stage

160.8 g (0.32 mol) of ditallow fatty amine (amine of the formula (III), where R has the meaning given in Example 1: iodine number: 50; alkali number: 111.7 mg KOH / g substance; molar mass 502.5 g / mol).
14.1 g (0.32 mol) ethylene oxide (EO)

2nd stage

2.2 g 40% aqueous KOH solution
70.4 g (1.6 mol) ethylene oxide (EO)

3rd stage

167.3 g (2.88 mol) propylene oxide (PO)
The product is an almost colorless, pasty mass with an alkali number of 45.0 mg KOH / g substance. The cloud point according to DIN 53971 cannot be determined.

Example 3

The product is produced analogously to Example 1.

Amounts used: 1st stage:

80.0 g (0.21 mol) of tallow fat dipropylenetriamine (amine of formula (V), where R has the meaning given in Example 1: iodine number: 32; alkali number: 433.1 mg KOH / g substance, molmase: 388.6 g / mol).
36.3 g (0.82 mol) ethylene oxide (EO)

2nd stage:

3.6 g 40% aqueous KOH solution
163.2 g (3.70 mol) ethylene oxide (EO)

3rd stage:

394.6 g (6.80 mol) propylene oxide (PO)
The product is a light brown, clear liquid with an alkali number of 56.2 mg KOH / g substance and has a cloud point of 41.8 ° C (according to DIN 53917).

Example 4

The product is produced analogously to Example 1.

1st stage:

51.1 g (0.15 mol) of tallow fat propylene diamine (amine of formula (IV), where R is the in Example 1 has the meaning given: iodine number 36; Alkaline number: 329 mg KOH / g substance; Molar mass: 340.7 g / mol).
19.8 g (0.45 mol) ethylene oxide (EO)

2nd stage:

2.6 g 40% aqueous KOH solution
125.5 g (2.85 mol) ethylene oxide (EO)

3rd stage:

287.5 g (4.95 mol) propylene oxide (PO)
The product is a light yellow, clear liquid; it has an alkali number of 32.5 mg KOH / g substance and a cloud point of 37.9 ° C (according to DIN 53917).

Preparation of the precursor for Examples 5 and 6 The preliminary stage 1st stage:

100.5 g (0.2 mol) ditallow fatty amine (amine of formula (III); composition see Example 2)
8.8 g (0.2 mol) ethylene oxide (EO)

2nd stage:

3.4 g of 40% aqueous KOH solution
96.9 g (2.2 mol) ethylene oxide (EO)

3rd stage:

325.2 g (5.6 mol) propylene oxide (PO)

Example 5

z in Tabelle I) umgesetzt. Die Umsetzung erfolgt analog Beispiel I, Stufe 2 (ohne Alkalisierungsschritt).Without further isolation, 530 g of the alkoxylated amine of stage 3 are mixed with 132.5 g of ethylene oxide (EO) (= 25% by weight, based on the alkoxylated amine of stage 3;

z implemented in Table I). The reaction is carried out analogously to Example I, stage 2 (without an alkalization step).

The product is a light brown, slightly cloudy liquid with an alkali number of 18.8 mg KOH / g substance and a cloud point of 52.2 ° C (according to DIN 53917).

Example 6

z in Tabelle I) umgesetzt. Die Umsetzung erfolgt analog Beispiel 1, Stufe 2 (ohne Alkalisierungsschritt).Without further isolation, 530 g of the alkoxylated amine of stage 3 are mixed with 79.5 g of ethylene oxide (EO) (= 15% by weight, based on the precursor;

z implemented in Table I). The reaction is carried out analogously to Example 1, stage 2 (without an alkalization step).

The product is a light brown, slightly cloudy liquid; it has an alkali number of 20.4 mg KOH / g substance and a cloud point of 42.7 ° C (according to DIN 53917).

Examples of use: a) Demulsification

For this purpose, the crude oil emulsions are poured into so-called torpedo glasses. Torpedo glasses are characterized by the fact that they taper down sharply and have a scale, which means that small volumes of separated water can be easily read. A defined amount of demulsifier is added to each of the torpedo glasses filled with the crude oil emulsions using a micro-dosing syringe.

It is then shaken well to distribute the demulsifiers as homogeneously as possible in the crude oil emulsions. Then the torpedo glasses filled with crude oil emulsion and demulsifier are placed in a tempered water bath and the separated amounts of water are read at constant intervals. The amounts of water separated are given in milliliters (ml) or in percent (%), based on the total amount of water present in the crude oil emulsion. The total amount of water present in the crude oil emulsion as well as the metered amount of demulsifier and the optimal cracking temperature must be determined before the demulsification test.

The crude oil emulsion of northern German origin used in the tests has a water content of approx. 68% and a salt content of approx. 18%.
In the experiments, an emulsion amount of 100 cm³ is used; the dewatering temperature is 50 ° C.
The amount (concentration) of demulsifier used in Examples 1 to 6 is 30 ppm each.
Table I shows the characteristics of the compounds of formula I. example Compounds of formula I. A R x [EO] y [PO] e.g. 1 II C₁₄-C₁₈ alkyl unsaturated 22 33 - 2nd III C₁₄-C₁₈ alkyl unsaturated 6 9 - 3rd V C₁₄-C₁₈ alkyl unsaturated 22 33 - 4th IV C₁₄-C₁₈ alkyl unsaturated 22 33 - 5 III C₁₄-C₁₈ alkyl unsaturated 12th 28 25th 6 III C₁₄-C₁₈ alkyl unsaturated 12th 28 15

The amount of water separated after 30, 60, 90, 180, 240 and 300 minutes is given in% of the total water (Table 2). example Time / minutes 30th 60 90 180 240 300 1 2nd 14 32 66 88 92 2nd 1 4th 12th 28 42 72 3rd 8th 26 74 96 98 100 4th 12th 36 80 96 98 100 5 20th 48 84 98 100 100 6 16 35 72 86 96 98

The results show that the compounds according to the invention have an excellent demulsifying effect.

b) corrosion inhibition

The test is carried out according to the Shell Wheel test. Coupons with a surface area of 15 cm² made of steel 1.1203 are dynamically aged in a mixture of salt water (5% by weight NaCl) and petroleum (9: 1) for 24 hours at 70 ° C, the pH of the aqueous Phase is set to 3.5 with acetic acid. The coupons are then cleaned and the weight loss determined. This test is a standard test for oil field corrosion inhibitors.

Table 3 lists the protection values in% of the compounds of the formula (I). The protection value is the reduction of the removal, ie the corrosion compared to the coupons without inhibitor in the liquid mixture. Table 3 example Amount used in ppm 5 10th 50 1 54 80 86 2nd 66 84 90 3rd 70 82 88 4th 68 83 87 5 48 78 83 6 52 80 84

The protection values achieved in this way in the laboratory test suggest good corrosion inhibition in the oil field.

c) Paraffin dispersion

For this, crude oil is pumped into a circuit above the temperature at which paraffin precipitates. In this circuit there is a U-shaped tube which can be immersed in a cooling bath. Bath and cooling temperatures are determined empirically, ie it must be checked in what time the U-tube clogs up with crystallizing paraffin. This is measured by the increase in performance of the pump or the increase in pressure. Inhibitors extend the time in which the U-tube clogs up and the pressure or the output of the pump reaches the same critical value.
In the laboratory, the conditions are selected so that the test is finished in about 6 to 8 hours; ie without the addition of an inhibitor, the critical values must be softened after one to a maximum of 2 hours. The ratio of time with inhibitor to without inhibitor (= time factor) is a measure of the inhibitor effect of the individual products.

The following time factors were achieved when using 200 ppm (Table 4): example Crude oil I Crude oil II 1 3.5 3.8 2nd 1.5 1.8 3rd 3.8 4.2 4th 4.6 4.4 5 4.4 4.6 6 3.8 4.6

These test results show that the compounds of the invention markedly retard paraffin deposits. In practice, this means: in probes with slight paraffin problems, constipation can be avoided by using the compounds according to the invention; or in the case of heavy paraffin deposits, the treatment intervals of the mechanical or thermal probe treatment can be greatly extended. This is very important for difficult to access, remote oil fields.

Claims (2)

Use of oxyalkylated fatty amines and fatty amine derivatives of the general formula (I)

in which
A is a radical of the formula (II) - (V)

with R equal to C₆-C₂₂-alkyl, preferably C₈-C₁₈-alkyl
x is a number from 5 to 40, preferably 8 to 20,
y is a number from 5 to 70, preferably 10-30 and
z is 0 to 70% by weight, preferably 0 to 40% by weight, of ethylene oxide, based on compounds of the formula (I) with x ethylene oxide units and y propylene units, as demulsifiers, corrosion inhibitors and / or pour point depressants. Use according to claim 1, characterized in that the oxyalkylated fatty amines and fatty amine derivatives of the formula (I) are added to the crude oil in an amount of 2-2000 ppm.